confessing her sins, adding:

Forgive me this my virtue;
For in the fatness of these pursy times
Virtue itself of vice must pardon beg
Yea, curb and woo for leave to do him good.

"Pursy" means "flabby" or "excessively wealthy," and "curb" means "to stoop" or "beg by stooping."  So, a translation of this, according to Enotes, is:

Forgive me my truth,
Because, in the fatness of these wealthy times
Virtue itself must beg pardon of vice,
Yes, beg and court for permission to do him good.

Hamlet uses allegory to personify virtue (goodness) and vice (wickedness).  He uses an ironic analogy (or paradox) to show that in Denmark virtue should be the law of the land, but vice has taken over.  As such, virtuous people must beg wicked people for the chance to do some good.

So, Hamlet (and his father's Ghost) represent virtue, and Gertrude, Claudius, Polonius (lying dead there), and all of their court spies represent vice.  In the famous Queen's closet scene here, Hamlet is ironically shaming his morally blind mother into realizing her sins and wickedness.